I got my MBP in August 2006 and in the past 2 months, it has also been having trouble reading audio CDs. Many of them get spat out.
For some reason, my Leopard disc and Aperture 2 disc, both of which I installed approx 2-3 weeks ago had no issue whatsoever.
I bought an LG external drive which is very solid and is much faster for ripping audio CDs so I just use that now.